Precision power level control for extended range wireless power transfer

ABSTRACT

A power transmitter for wireless power transfer includes a control and communications unit configured to provide power control signals to a power supply external to the power transmitter for controlling a power level of a power signal configured for transmission to a power receiver, the power supply configured to configure a direct current (DC) power based on the power control signals. The power transmitter further includes an inverter circuit configured to receive the DC power from the power supply external to the power transmitter and convert the input power to a power signal. The power transmitter further includes a coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face and shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil.

TECHNICAL FIELD

The present disclosure generally relates to systems and methods forwireless transfer of electrical power and, more particularly, toprecision power level control for wireless power transmitters,transmitting at extended separation distances.

BACKGROUND

Wireless power transfer systems are used in a variety of applicationsfor the wireless transfer of electrical energy, electrical powersignals, electromagnetic energy, electrical data signals, among otherknown wirelessly transmittable signals. Such systems often use inductivewireless power transfer, which occurs when magnetic fields created by atransmitting element induce an electric field, and hence, an electriccurrent, in a receiving element. These transmission and receiverelements will often take the form of coiled wires and/or antennas.

Because some wireless power transfer systems are operable and/or mostefficient in the near-field, some transmitters may be limited to havingoperability only at restrictively small gaps between the transmittercoil and the receiver coil. To that end, typical wireless powertransmitters under the Wireless Power Consortium's Qi™ standard may belimited to operability at a maximum coil-to-coil separation gap (whichmay be referred to herein as a “separation gap” or “gap”) of about 3millimeters (mm) to about 5 mm. The separation gap is sometimes known asthe Z-height or Z-distance and is generally measured as the distancebetween the transmitter coil and receiver coil.

As the adoption of wireless power grows, commercial applications arerequiring a power transmitter capable of transferring power to a powerreceiver with a gap greater than 3-5 mm. By way of example, cabinetsand/or counter tops may be more than 3-5 mm thick and as a result,prevent wireless charging through such furniture. As another example,modern mobile devices may be used with cases, grip devices, and/orwallets, among other things, that can obstruct wireless powertransmission to the mobile device and/or create a separation gap thatdisallows operability of wireless power transmission. Legacy wirelesspower transmitter designs further may be incapable of desired commercialapplications (e.g., through object chargers, under table chargers,infrastructure chargers, ruggedized computing device charging, amongother things), due to the limitations in separation gap inherent tolegacy, near-field wireless power transfer systems. Increasing theseparation gap, while keeping satisfactory performance (e.g., thermalperformance, transfer/charging speed, efficiency, etc.) will increasethe number of commercial applications that can utilize wireless power.

Further, current standards specifications, regulations, and/or end-userproduct specifications may require particular power levels, fortransmission to a power receiver. To that end, the power receiver mayhave particular power requests and/or particular limits for efficiency,safety, and/or any other power control reasons.

SUMMARY

New wireless power transmitters and/or associated base stations aredesired that are capable of delivering wireless power signals to a powerreceiver at a separation gap larger than the about 3 mm to about 5 mmseparation gaps of legacy transmitters. Further, wireless powertransmitters at such larger gap distances may require and/or may beenhanced via more precision and/or granular power controls.

In an embodiment, the overall structure of the transmitter is configuredin a way that allows the transmitter to transfer power at an operatingfrequency of about 87 kilohertz (kHz) to about 205 kHz and achieve thesame and/or enhanced relative characteristics (e.g., rate of powertransfer, speed of power transfer, power level, power level management,among other things) of power transfer as legacy transmitters thatoperated in that frequency range. As a result, the separation gap may beincreased from about 3-5 mm to around 15 mm or greater using the overallstructure of the transmitter. In an embodiment, a transmitter may beconfigured with a ferrite core that substantially surrounds thetransmitter antenna on three sides. The only place that the ferrite coredoes not surround the transmitter antenna is on the top (e.g., in thedirection of power transfer) and where the power lines connect to thetransmitter antenna. This overall structure of the transmitter allowsfor the combination of power transfer characteristics, power levelcharacteristics, self-resonant frequency restraints, designrequirements, adherence to standards bodies' required characteristics,bill of materials (BOM) and/or form factor constraints, among otherthings, that allow for power transfer over larger separation gaps.

Transmission of one or more of electrical energy, electrical power,electromagnetic energy or electronic data signals from one of suchcoiled antennas to another, generally, operates at an operatingfrequency and/or an operating frequency range. The operating frequencymay be selected for a variety of reasons, such as, but not limited to,power transfer characteristics, power level characteristics,self-resonant frequency restraints, design requirements, adherence tostandards bodies' required characteristics, bill of materials (BOM)and/or form factor constraints, among other things. It is to be notedthat, “self-resonating frequency,” as known to those having skill in theart, generally refers to the resonant frequency of an inductor due tothe parasitic characteristics of the component.

In some examples, power profiles, such as those defined by the QiStandard, may require more sophisticated and/or precision controls,compared to legacy wireless power transmitters. Such examples mayinvolve higher power input to the wireless power transmitter and, thus,more expensive and/or complicated voltage regulation mechanisms may berequired in the power conditioning system and/or amplifier design. Tothat end, utilizing the systems and methods disclosed herein, suchvoltage regulation mechanisms may be removed from the wireless powertransmitter and the wireless power transmitter may utilize controlschemes, disclosed herein, to control the input power to the wirelesspower transmitter, via communications with an external input powersource. By utilizing communications with the external power source, billof materials (BOM) may be decreased, for such power transmitters,resulting in lower cost power transmitters. Additionally oralternatively, by utilizing such control schemes, the power transmittersutilizing said schemes, disclosed herein, may have greater compatibilityand/or performance when utilized with off-the-shelf power supplies(e.g., Universal Serial Bus (USB) power supplies, Lightning powersupplies, Qualcomm Quick Charge devices, USB-C power supplies, USB-PD(USB Power Delivery) power supplies, Mini-USB power supplies,proprietary power supplies, input/outputs on electronic devices (e.g., acomputer, a multi device charger, an automobile console, a mobiledevice, a portable power supply, a battery, a generator, among otherthings).

In accordance with one aspect of the disclosure, a power transmitter forwireless power transfer at an operating frequency selected from a rangeof about 87 kilohertz (kHz) to about 205 kHz is disclosed. The powertransmitter includes a control and communications unit configured toprovide power control signals to control a power level of a power signalconfigured for transmission to a power receiver. The power transmitterfurther includes an inverter circuit configured to receive a directcurrent (DC) power from a power supply external to the power transmitterand convert the input power to a power signal. The power transmitterfurther includes a coil configured to transmit the power signal to apower receiver, the coil formed of wound Litz wire and including atleast one layer, the coil defining, at least, a top face, and ashielding comprising a ferrite core and defining a cavity, the cavityconfigured such that the ferrite core substantially surrounds all butthe top face of the coil.

In a refinement, the control and communications unit is furtherconfigured to receive power request signals from the power receiver anddetermine the power control signals based on the power request signals.

In a refinement, the control and communications unit is configured toprovide the power control signals to the power supply external to thepower transmitter and the power supply is configured to configure aninput DC power to generate the DC power supplied based on the powercontrol signals and provide the DC power the inverter circuit.

In a further refinement, the power supply includes a voltage regulatorand a power supply controller configured to receive the power controlsignals, generate voltage regulation instructions for altering a DCvoltage of the DC power, based on the power control signals, and providethe voltage regulation instructions to the voltage regulator to controlthe DC voltage of the DC power.

In yet a further refinement, the voltage regulation instructions includevoltage step up instructions or voltage step down instructions for thevoltage regulator, the voltage step up instructions and voltage stepdown instructions having a step level, the step level being a change involtage at which the voltage regulator is configured to step up or stepdown the DC voltage of the DC power.

In yet a further refinement, the step level is in a range of about 10millivolts (mV) to about 500 mV.

In yet another further refinement, the step level is about 200 mV.

In a further refinement, the power signal is an alternating current (AC)power signal having a root mean square voltage and the control andcommunications circuit is configured to generate a pulse widthmodulation signal for configuring an alternating current (AC) frequencyfor the power signal, at the operating frequency, the pulse widthmodulation signals modified by a duty cycle alteration, the duty cyclealteration configured to decrease the root means square voltage of thepower signal.

In yet a further refinement, the output power has a root mean squarevoltage, the root means square voltage being less than the stepped up orstepped down DC voltage.

In a refinement, the control and communications circuit is configured togenerate a pulse width modulation signal for configuring an alternatingcurrent (AC) frequency for the power signals at the operating frequency,the pulse width modulation signals modified by a duty cycle alteration,the duty cycle alteration configured to alter an amount of powertransmitted to the power receiver over a period of time.

In accordance with another aspect of the disclosure, a power transmitterfor wireless power transfer at an operating frequency selected from arange of about 87 kilohertz (kHz) to about 205 kHz is disclosed. Thepower transmitter includes a control and communications unit configuredto provide power control signals to a power supply external to the powertransmitter for controlling a power level of a power signal configuredfor transmission to a power receiver, the power supply configured toconfigure a direct current (DC) power based on the power controlsignals. The power transmitter further includes an inverter circuitconfigured to receive the DC power from the power supply external to thepower transmitter and convert the input power to a power signal. Thepower transmitter further includes a coil configured to transmit thepower signal to a power receiver, the coil formed of wound Litz wire andincluding at least one layer, the coil defining, at least, a top faceand shielding comprising a ferrite core and defining a cavity, thecavity configured such that the ferrite core substantially surrounds allbut the top face of the coil.

In a refinement, the shielding is an E-Core type shielding and thecavity is configured in an E-shape configuration.

In a refinement, a shielding outer edge of the shielding extends about4.5 millimeters (mm) to about 6.5 mm outward from a coil outer edge ofthe coil.

In a refinement, the coil has an outer diameter length in a range ofabout 40 mm to about 50 mm.

In a refinement, the coil has an inner diameter length in a range ofabout 15 mm to about 25 mm.

In a refinement, the at least one layer comprises a first layer and asecond layer.

In a further refinement, the first layer includes a first number ofturns in a range of about 4 turns to about 5 turns, and wherein thesecond layer includes a second number of turns in a range of about 4turns to about 5 turns.

In accordance with another aspect of the disclosure, a system forwireless power transfer at an operating frequency selected from a rangeof about 87 kilohertz (kHz) to about 205 kHz is disclosed. The systemincludes a power transmitter and a power supply. The power transmitterincludes a control and communications unit configured to provide powercontrol signals for controlling a power level of a power signalconfigured for transmission to a power receiver and an inverter circuitconfigured to receive a direct current (DC) power and convert the inputpower to a power signal. The power transmitter further includes a coilconfigured to transmit the power signal to a power receiver, the coilformed of wound Litz wire and including at least one layer, the coildefining, at least, a top face and a shielding comprising a ferrite coreand defining a cavity, the cavity configured such that the ferrite coresubstantially surrounds all but the top face of the coil. The powersupply is external to the power transmitter, the power supply configuredto configure the DC power based on the power control signals. The powersupply includes a voltage regulator and a power supply controllerconfigured to receive the input power signals, generate voltageregulation instructions for altering the DC input power, based on thepower control signals, the voltage regulation instructions includingvoltage step up instructions or voltage step down instructions for theDC/DC convertor, the voltage step up instructions and voltage step downinstructions having a step level, the step level being a change involtage at which the voltage regulator is configured to step up or stepdown the DC voltage of the DC power, and provide the voltage regulationinstructions to the voltage regulator to control a DC voltage of the DCpower.

These and other aspects and features of the present disclosure will bebetter understood when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary block diagram of an embodiment of a wirelesspower transfer system, in accordance with an embodiment of the presentdisclosure.

FIG. 2 is an exemplary block diagram for a power transmitter, which maybe used in conjunction with the wireless power transfer system of FIG.1, in accordance with FIG. 1 and an embodiment of the presentdisclosure.

FIG. 3 is an exemplary block diagram for components of a control andcommunications system of the power transmitter of FIG. 2, in accordancewith FIGS. 1-2 and an embodiment of the present disclosure.

FIG. 4 is an exemplary block diagram for components of a sensing systemof the control and communications system of FIG. 3, in accordance withFIGS. 1-3 and an embodiment of the present disclosure.

FIG. 5 is an exemplary block diagram for components of a powerconditioning system of the power transmitter of FIGS. 1-2, in accordancewith FIGS. 1-2 and an embodiment of the present disclosure.

FIG. 6A is an exemplary block diagram for components of the powertransmitter of FIGS. 1-5 and an external power supply of the wirelesspower transfer system of FIG. 1, in accordance with FIGS. 1-5 and thepresent disclosure.

FIG. 6B is an exemplary block diagram illustrating similar components ofthe power transmitter as those of FIG. 6A, but further illustrating aduty cycle shift in the process of generating a power signal, inaccordance with FIGS. 1-6A and the present disclosure.

FIG. 6C is an exemplary block diagram illustrating components and/orfunctions associated with one or more of a transmitter controller, apulse width modulation generator, or components thereof of FIGS. 6A and6B, in accordance with FIGS. 1-6B and the present disclosure.

FIG. 7 is a block diagram for a method of controlling power output inthe wireless power transmitter of FIGS. 1-6 and utilizing elementsillustrated in FIG. 6, in accordance with FIGS. 1-6 and the presentdisclosure.

FIG. 8 is an exemplary electrical schematic diagram of components of thepower transmitter of FIGS. 1-7, in accordance with FIGS. 1-7 and thepresent disclosure.

FIG. 9 is a perspective view of a shape of a transmitter coil of thepower transmitter of FIGS. 1-8, in accordance with FIGS. 1-8 and anembodiment of the present disclosure.

FIG. 10 is a cross-section of components of a base station, with whichthe power transmitter 20 is associated, in accordance with FIGS. 1-9 andthe present disclosure.

FIG. 11 is a perspective view of a shielding associated with thetransmitter coil of FIGS. 1-10, in accordance with FIGS. 1-10 and anembodiment of the present disclosure.

FIG. 12A is a perspective view of the transmitter coil of FIGS. 1-11 andthe shielding of FIGS. 10 and 11, in accordance with FIGS. 1-11 and thepresent disclosure.

FIG. 12B is an exploded perspective view of the transmitter coil ofFIGS. 1-10 and the shielding of FIGS. 10 and 11, in accordance withFIGS. 1-12A and the present disclosure.

FIG. 13A is an exemplary block diagram for an embodiment of the basestation of FIGS. 1-10 in accordance with FIGS. 1-12 and the presentdisclosure.

FIG. 13B is an exemplary block diagram for another embodiment of thebase station of FIGS. 1-10 in accordance with FIGS. 1-12 and the presentdisclosure.

FIG. 14 is a readout of an actual simulation of magnetic fieldsgenerated by the coils and/or transmitters illustrated in FIGS. 1-13 anddisclosed herein.

FIG. 15 is a flow chart for an exemplary method for designing a powertransmitter, in accordance with FIGS. 1-14 and the present disclosure.

FIG. 16 is a flow chart for an exemplary method for manufacturing apower transmitter, in accordance with FIGS. 1-14 and the presentdisclosure.

While the following detailed description will be given with respect tocertain illustrative embodiments, it should be understood that thedrawings are not necessarily to scale and the disclosed embodiments aresometimes illustrated diagrammatically and in partial views. Inaddition, in certain instances, details which are not necessary for anunderstanding of the disclosed subject matter or which render otherdetails too difficult to perceive may have been omitted. It shouldtherefore be understood that this disclosure is not limited to theparticular embodiments disclosed and illustrated herein, but rather to afair reading of the entire disclosure and claims, as well as anyequivalents thereto. Additional, different, or fewer components andmethods may be included in the systems and methods.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth byway of examples in order to provide a thorough understanding of therelevant teachings. However, it should be apparent to those skilled inthe art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and/or circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

Referring now to the drawings and with specific reference to FIG. 1, awireless power transfer system 10 is illustrated. The wireless powertransfer system 10 provides for the wireless transmission of electricalsignals, such as, but not limited to, electrical energy, electricalpower signals, and electromagnetic energy. Additionally, the wirelesspower transfer system 10 may provide for wireless transmission ofelectronically transmittable data (“electronic data”) independent ofand/or associated with the aforementioned electrical signals.Specifically, the wireless power transfer system 10 provides for thewireless transmission of electrical signals via near field magneticcoupling. As shown in the embodiment of FIG. 1, the wireless powertransfer system 10 includes a power transmitter 20 and a power receiver30. The power receiver 30 is configured to receive electrical energy,electrical power, electromagnetic energy, and/or electronic data from,at least, the power transmitter 20.

As illustrated, the power transmitter 20 and power receiver 30 may beconfigured to transmit electrical energy, via transmitter antenna 21 andreceiver antenna 31, electrical power, electromagnetic energy, and/orelectronically transmittable data across, at least, a separationdistance or gap 17. A separation distance or gap, such as the gap 17, inthe context of a wireless power transfer system, such as the system 10,does not include a physical connection, such as a wired connection.There may be intermediary objects located in a separation distance orgap, such as the gap 17, such as, but not limited to, air, a countertop, a casing for an electronic device, a grip device for a mobiledevice, a plastic filament, an insulator, a mechanical wall, among otherthings; however, there is no physical, electrical connection at such aseparation distance or gap.

The combination of the power transmitter 20 and the power receiver 30create an electrical connection without the need for a physicalconnection. “Electrical connection,” as defined herein, refers to anyfacilitation of a transfer of an electrical current, voltage, and/orpower from a first location, device, component, and/or source to asecond location, device, component, and/or destination. An “electricalconnection” may be a physical connection, such as, but not limited to, awire, a trace, a via, among other physical electrical connections,connecting a first location, device, component, and/or source to asecond location, device, component, and/or destination. Additionally oralternatively, an “electrical connection” may be a wireless electricalconnection, such as, but not limited to, magnetic, electromagnetic,resonant, and/or inductive field, among other wireless electricalconnections, connecting a first location, device, component, and/orsource to a second location, device, component, and/or destination.

Alternatively, the gap 17 may be referenced as a “Z-Distance,” because,if one considers an antenna 21, 31 to be disposed substantially along acommon X-Y plane, then the distance separating the antennas 21, 31 isthe gap in a “Z” or “depth” direction. However, flexible and/ornon-planar coils are certainly contemplated by embodiments of thepresent disclosure and, thus, it is contemplated that the gap 17 may notbe uniform, across an envelope of connection distances between theantennas 21, 31. It is contemplated that various tunings,configurations, and/or other parameters may alter the possible maximumdistance of the gap 17, such that electrical transmission from the powertransmitter 20 to the power receiver 30 remains possible.

The wireless power transfer system 10 operates when the powertransmitter 20 and the power receiver 30 are coupled. As defined herein,the terms “couples,” “coupled,” and “coupling” generally refers tomagnetic field coupling, which occurs when the energy of a transmitterand/or any components thereof and the energy of a receiver and/or anycomponents thereof are coupled to each other through a magnetic field.Coupling of the power transmitter 20 and the power receiver 30, in thesystem 10, may be represented by a resonant coupling coefficient of thesystem 10 and, for the purposes of wireless power transfer, the couplingcoefficient for the system 10 may be in the range of about 0.01 and 0.9.

The power transmitter 20 may be operatively associated with a basestation 11. The base station 11 may be a device, such as a charger, thatis able to provide near-field inductive power, via the power transmitter20, to a power receiver. In some examples, the base station 11 may beconfigured to provide such near-field inductive power as specified inthe Qi™ Wireless Power Transfer System, Power Class 0 Specification. Insome such examples, the base station 11 may carry a logo to visuallyindicate to a user that the base station 11 complies with the Qi™Wireless Power Transfer System, Power Class 0 Specification.

The power transmitter 20 may receive power from an input power source12. The base station 11 may be any electrically operated device, circuitboard, electronic assembly, dedicated charging device, or any othercontemplated electronic device. Example base stations 11, with which thepower transmitter 20 may be associated therewith, include, but are notlimited to including, a device that includes an integrated circuit,cases for wearable electronic devices, receptacles for electronicdevices, a portable computing device, clothing configured withelectronics, storage medium for electronic devices, charging apparatusfor one or multiple electronic devices, dedicated electrical chargingdevices, activity or sport related equipment, goods, and/or datacollection devices, among other contemplated electronic devices.

The input power source 12 may be or may include one or more electricalstorage devices, such as an electrochemical cell, a battery pack, and/ora capacitor, among other storage devices. Additionally or alternatively,the input power source 12 may be any electrical input source (e.g., anyalternating current (AC) or direct current (DC) delivery port) and mayinclude connection apparatus from said electrical input source to thewireless transmission system 20 (e.g., transformers, regulators,conductive conduits, traces, wires, or equipment, goods, computer,camera, mobile phone, and/or other electrical device connection portsand/or adaptors, such as but not limited to USB or lighting ports and/oradaptors, among other contemplated electrical components). Further, asillustrated, the input power source 12 may include, may be implementedby, and/or may be operatively associated with, for the purpose of powerdistribution, an external power supply 45, which directly provides adirect current (DC) power input to the power transmitter 20. Theexternal power supply 45 may include or comprise one or more UniversalSerial Bus (USB) power supplies, Lightning power supplies, QualcommQuick Charge devices, USB-C power supplies, USB-PD (USB Power Delivery)power supplies, Mini-USB power supplies, proprietary power supplies,input/outputs on electronic devices (e.g., a computer, a multi devicecharger, an automobile console, a mobile device, a portable powersupply, a battery, a generator, among known power supplies.

Electrical energy received by the power transmitter 20 is then used forat least two purposes: providing electrical power to internal componentsof the power transmitter 20 and providing electrical power to thetransmitter coil 21. The transmitter coil 21 is configured to wirelesslytransmit the electrical signals conditioned and modified for wirelesstransmission by the power transmitter 20 via near-field magneticcoupling (NFMC). Near-field magnetic coupling enables the transfer ofelectrical energy, electrical power, electromagnetic energy, and/orelectronically transmissible data wirelessly through magnetic inductionbetween the transmitter coil 21 and a receiving coil 31 of, orassociated with, the power receiver 30. Near-field magnetic coupling mayenable “inductive coupling,” which, as defined herein, is a wirelesspower transmission technique that utilizes an alternatingelectromagnetic field to transfer electrical energy between two or moreantennas/coils. Such inductive coupling is the near field wirelesstransmission of electrical energy between two magnetically coupled coilsthat are tuned to resonate at a similar frequency. Further, suchnear-field magnetic coupling may provide connection via “mutualinductance,” which, as defined herein is the production of anelectromotive force in a circuit by a change in current in at least onecircuit magnetically coupled to the first.

In one or more embodiments, the inductor coils of either the transmittercoil 21 or the receiver coil 31 are strategically positioned tofacilitate reception and/or transmission of wirelessly transferredelectrical energy, power, electromagnetic energy and/or data throughnear field magnetic induction. Antenna operating frequencies maycomprise all operating frequency ranges, examples of which may include,but are not limited to, about 87 kHz to about 205 kHz (Qi™ interfacestandard). The operating frequencies of the coils 21, 31 may beoperating frequencies designated by the International TelecommunicationsUnion (ITU) in the Industrial, Scientific, and Medical (ISM) frequencybands.

As known to those skilled in the art, a “resonant frequency” or“resonant frequency band” refers to a frequency or frequencies whereinamplitude response of the antenna is at a relative maximum, or,additionally or alternatively, the frequency or frequency band where thecapacitive reactance has a magnitude substantially similar to themagnitude of the inductive reactance. In one or more embodiments thetransmitting antenna resonant frequency band extends from about 87 kHzto about 205 kHz. In one or more embodiments the inductor coil of thereceiver coil 31 is configured to resonate at a receiving antennaresonant frequency or within a receiving antenna resonant frequencyband.

In some examples, the transmitting coil and the receiving coil of thepresent disclosure may be configured to transmit and/or receiveelectrical power at a baseline power profile having a magnitude up toabout 5 watts (W). In some other examples, the transmitting coil and thereceiving coil of the present disclosure may be configured to transmitand/or receive electrical power at an extended power profile, supportingtransfer of up to 15 W of power.

The power receiver 30 is configured to acquire near-field inductivepower from the power transmitter 20. In some examples, the powerreceiver 30 is a subsystem of an electronic device 14. The electronicdevice 14 may be any device that is able to consume near field inductivepower as specified in the Qi™ Wireless Power Transfer System, PowerClass 0 Specification. In some such examples, the electronic device 14may carry a logo to visually indicate to a user that the electronicdevice 14 complies with the Specification.

The electronic device 14 may be any device that requires electricalpower for any function and/or for power storage (e.g., via a batteryand/or capacitor). Additionally or alternatively, the electronic device14 may be any device capable of receipt of electronically transmissibledata. For example, the device may be, but is not limited to being, ahandheld computing device, a mobile device, a portable appliance, anintegrated circuit, an identifiable tag, a kitchen utility device, anautomotive device, an electronic tool, an electric vehicle, a gameconsole, a robotic device, a wearable electronic device (e.g., anelectronic watch, electronically modified glasses, altered-reality (AR)glasses, virtual reality (VR) glasses, among other things), a portablescanning device, a portable identifying device, a sporting good, anembedded sensor, an Internet of Things (IoT) sensor, IoT enabledclothing, IoT enabled recreational equipment, industrial equipment,medical equipment, a medical device, a tablet computing device, aportable control device, a remote controller for an electronic device, agaming controller, among other things.

For the purposes of illustrating the features and characteristics of thedisclosed embodiments, arrow-ended lines are utilized to illustratetransferrable and/or communicative signals and various patterns are usedto illustrate electrical signals that are intended for powertransmission and electrical signals that are intended for thetransmission of data and/or control instructions. Solid lines indicatesignal transmission of electrical energy, electrical power signals,and/or electromagnetic energy over a physical and/or wireless electricalconnection, in the form of power signals that are, ultimately, utilizedin wireless power transmission from the power transmitter 20 to thepower receiver 30. Further, dotted lines are utilized to illustrateelectronically transmittable data signals, which ultimately may bewirelessly transmitted from the power transmitter 20 to the powerreceiver 30.

Turning now to FIG. 2, the wireless power transfer system 10 isillustrated as a block diagram including example sub-systems of thepower transmitter 20. The wireless transmission system 20 may include,at least, a power conditioning system 40, a control and communicationssystem 26, a sensing system 50, and the transmission coil 21. Theelectrical energy input from the input power source 12, via the externalpower supply 45, is conditioned and/or modified for wireless powertransmission, to the power receiver 30, via the transmission coil 21.Accordingly, the second portion of the input energy is modified and/orconditioned by the power conditioning system 40.

The control and communications system 26, generally, comprises digitallogic portions of the power transmitter 20. The control andcommunications system 26 receives and decodes messages from the powerreceiver 30, executes the relevant power control algorithms andprotocols, and drives the frequency of the AC waveform to control thepower transfer. As discussed in greater detail below, the control andcommunications system 26 also interfaces with other subsystems of thepower transmitter 20. For example, the control and communications system26 may interface with other elements of the power transmitter 20 foruser interface purposes.

Referring now to FIG. 3, with continued reference to FIGS. 1 and 2,subcomponents and/or systems of the control and communications system 26are illustrated. The control and communications system 26 may include atransmission controller 28, a communications system 29, a driver 48, anda memory 27.

The transmission controller 28 may be any electronic controller orcomputing system that includes, at least, a processor which performsoperations, executes control algorithms, stores data, retrieves data,gathers data, controls and/or provides communication with othercomponents and/or subsystems associated with the power transmitter 20,and/or performs any other computing or controlling task desired. Thetransmission controller 28 may be a single controller or may includemore than one controller disposed to control various functions and/orfeatures of the power transmitter 20 such as, but not limited to,providing control instructions to the external power supply 45.Functionality of the transmission controller 28 may be implemented inhardware and/or software and may rely on one or more data maps relatingto the operation of the power transmitter 20. To that end, thetransmission controller 28 may be operatively associated with the memory27. The memory may include one or more of internal memory, externalmemory, and/or remote memory (e.g., a database and/or server operativelyconnected to the transmission controller 28 via a network, such as, butnot limited to, the Internet). The internal memory and/or externalmemory may include, but are not limited to including, one or more of aread only memory (ROM), including programmable read-only memory (PROM),erasable programmable read-only memory (EPROM or sometimes but rarelylabelled EROM), electrically erasable programmable read-only memory(EEPROM), random access memory (RAM), including dynamic RAM (DRAM),static RAM (SRAM), synchronous dynamic RAM (SDRAM), single data ratesynchronous dynamic RAM (SDR SDRAM), double data rate synchronousdynamic RAM (DDR SDRAM, DDR2, DDR3, DDR4), and graphics double data ratesynchronous dynamic RAM (GDDR SDRAM, GDDR2, GDDR3, GDDR4, GDDR5, a flashmemory, a portable memory, and the like. Such memory media are examplesof nontransitory machine readable and/or computer readable memory media.

While particular elements of the control and communications system 26are illustrated as independent components and/or circuits (e.g., thedriver 48, the memory 27, the communications system 29, among othercontemplated elements) of the control and communications system 26, suchcomponents may be integrated with the transmission controller 28. Insome examples, the transmission controller 28 may be an integratedcircuit configured to include functional elements of one or both of thetransmission controller 28 and the power transmitter 20, generally.

As illustrated, the transmission controller 28 is in operativeassociation, for the purposes of data transmission, receipt, and/orcommunication, with, at least, the memory 27, the communications system29, the power conditioning system 40, the driver 48, and the sensingsystem 50. The driver 48 may be implemented to control, at least inpart, the operation of the power conditioning system 40. In someexamples, the driver 48 may receive instructions from the transmissioncontroller 28 to output a generated pulse width modulation (PWM) signalto the power conditioning system 40. In some such examples, the PWMsignal may be configured to drive the power conditioning system 40 tooutput electrical power as an alternating current signal, having anoperating frequency defined by the PWM signal. As discussed in greaterdetail below with reference to FIGS. 6-7B, the PWM signal may be alteredby the controller 28, for, at least, power control purposes.

The sensing system 50 may include one or more sensors, wherein eachsensor may be operatively associated with one or more components of thepower transmitter 20 and configured to provide information and/or data.The term “sensor” is used in its broadest interpretation to define oneor more components operatively associated with the power transmitter 20that operate to sense functions, conditions, electrical characteristics,operations, and/or operating characteristics of one or more of the powertransmitter 20, the power receiver 30, the input power source 12, thebase station 11, the transmission coil 21, the receiver coil 31, alongwith any other components and/or subcomponents thereof.

As illustrated in the embodiment of FIG. 4, the sensing system 50 mayinclude, but is not limited to including, a thermal sensing system 52,an object sensing system 54, a receiver sensing system 56, electricalsensor(s) 57 and/or any other sensor(s) 58. Within these systems, theremay exist even more specific optional additional or alternative sensingsystems addressing particular sensing aspects required by anapplication, such as, but not limited to: a condition-based maintenancesensing system, a performance optimization sensing system, astate-of-charge sensing system, a temperature management sensing system,a component heating sensing system, an IoT sensing system, an energyand/or power management sensing system, an impact detection sensingsystem, an electrical status sensing system, a speed detection sensingsystem, a device health sensing system, among others. The object sensingsystem 54, may be a foreign object detection (FOD) system.

Each of the thermal sensing system 52, the object sensing system 54, thereceiver sensing system 56 and/or the other sensor(s) 58, including theoptional additional or alternative systems, are operatively and/orcommunicatively connected to the transmission controller 28. The thermalsensing system 52 is configured to monitor ambient and/or componenttemperatures within the power transmitter 20 or other elements nearbythe power transmitter 20. The thermal sensing system 52 may beconfigured to detect a temperature within the power transmitter 20 and,if the detected temperature exceeds a threshold temperature, thetransmission controller 28 prevents the power transmitter 20 fromoperating. Such a threshold temperature may be configured for safetyconsiderations, operational considerations, efficiency considerations,and/or any combinations thereof. In a non-limiting example, if, viainput from the thermal sensing system 52, the transmission controller 28determines that the temperature within the power transmitter 20 hasincreased from an acceptable operating temperature to an undesiredoperating temperature (e.g., in a non-limiting example, the internaltemperature increasing from about 20° Celsius (C) to about 50° C., thetransmission controller 28 prevents the operation of the powertransmitter 20 and/or reduces levels of power output from the powertransmitter 20. In some non-limiting examples, the thermal sensingsystem 52 may include one or more of a thermocouple, a thermistor, anegative temperature coefficient (NTC) resistor, a resistancetemperature detector (RTD), and/or any combinations thereof.

As depicted in FIG. 4, the transmission sensing system 50 may includethe object sensing system 54. The object sensing system 54 may beconfigured to detect presence of unwanted objects in contact with orproximate to the power transmitter 20. In some examples, the objectsensing system 54 is configured to detect the presence of an undesiredobject. In some such examples, if the transmission controller 28, viainformation provided by the object sensing system 54, detects thepresence of an undesired object, then the transmission controller 28prevents or otherwise modifies operation of the power transmitter 20. Insome examples, the object sensing system 54 utilizes an impedance changedetection scheme, in which the transmission controller 28 analyzes achange in electrical impedance observed by the transmission coil 21against a known, acceptable electrical impedance value or range ofelectrical impedance values. Additionally or alternatively, in someexamples the object sensing system 54 may determine if a foreign objectis present by measuring power output associated with the powertransmitter 20 and determining power input associated with a receiverassociated with the power transmitter 20. In such examples, the objectsensing system 54 may calculate a difference between the powerassociated with the power transmitter 20 and the power associated withthe receiver and determine if the difference indicates a loss,consistent with a foreign object not designated for wireless powertransmission.

Additionally or alternatively, the object sensing system 54 may utilizea quality factor (Q) change detection scheme, in which the transmissioncontroller 28 analyzes a change from a known quality factor value orrange of quality factor values of the object being detected, such as thereceiver coil 31. The “quality factor” or “Q” of an inductor can bedefined as (frequency (Hz)×inductance (H))/resistance (ohms), wherefrequency is the operational frequency of the circuit, inductance is theinductance output of the inductor and resistance is the combination ofthe radiative and reactive resistances that are internal to theinductor. “Quality factor,” as defined herein, is generally accepted asan index (figure of measure) that measures the efficiency of anapparatus like an antenna, a circuit, or a resonator. In some examples,the object sensing system 54 may include one or more of an opticalsensor, an electro-optical sensor, a Hall effect sensor, a proximitysensor, and/or any combinations thereof.

The receiver sensing system 56 is any sensor, circuit, and/orcombinations thereof configured to detect presence of any wirelessreceiving system that may be couplable with the power transmitter 20. Insome examples, if the presence of any such wireless receiving system isdetected, wireless transmission of electrical energy, electrical power,electromagnetic energy, and/or data by the power transmitter to saidwireless receiving system is enabled. In some examples, if the presenceof a wireless receiver system is not detected, wireless transmission ofelectrical energy, electrical power, electromagnetic energy, and/or datais prevented from occurring. Accordingly, the receiver sensing system 56may include one or more sensors and/or may be operatively associatedwith one or more sensors that are configured to analyze electricalcharacteristics within an environment of or proximate to the powertransmitter 20 and, based on the electrical characteristics, determinepresence of a power receiver 30.

The electrical sensor(s) 57 may include any sensors configured fordetecting and/or measuring any current, voltage, and/or power within thepower transmitter 20. Information provided by the electrical sensor(s)57, to the transmission controller 28, may be utilized independentlyand/or in conjunction with any information provided to the transmissioncontroller 28 by one or more of the thermal sensing system 52, theobject sensing system 54, the receiver sensing system 56, the othersensor(s) 58, and any combinations thereof.

Referring now to FIG. 5, and with continued reference to FIGS. 1-4, ablock diagram illustrating an embodiment of the power conditioningsystem 40 is illustrated. At the power conditioning system 40,electrical power is received, generally, as a DC power source, via theexternal power supply 45. The electrical power is provided to anamplifier 42 of the power conditioning system 40, which is configured tocondition the electrical power for wireless transmission by the coil 21.The amplifier 42 may function as an inverter, which receives a DC powersignal from the external power supply 45 and generates an AC powersignal as output, based, at least in part, on PWM input from thetransmission control system 26. The amplifier 42 may be or include, forexample, a power stage inverter. The use of the amplifier 42 within thepower conditioning system 40 and, in turn, the power transmitter 20enables wireless transmission of electrical signals having much greateramplitudes than if transmitted without such an amplifier. For example,the addition of the amplifier 42 may enable the wireless transmissionsystem 20 to transmit electrical energy as an electrical power signalhaving electrical power from about 10 milliwatts (mW) to about 60 W.

Turning now to FIGS. 6A and 6B, with continued reference to FIGS. 1-5,components of the power transmitter 20 and the external power supply 45are illustrated, for the purposes of describing power control methods,schemes, and/or components of the power transmitter 20. To that end, theblock diagram of FIG. 6A illustrates interaction between one or more ofthe power conditioning system 40, the amplifier 42, the controller 28,the external power supply 45, or components thereof.

The external power supply 45, as discussed above, may be any suitablepower supply, which is configurable for providing a proper DC powersignal (V_(DC)), at a DC voltage, to the amplifier 42. The DC power isconditioned for wireless power transmission as an alternating current(AC) power signal (V_(AC)), via the transmitter antenna 21. In someexamples, the external power supply 45 may provide V_(DC) directly tothe amplifier 42, absent any additional voltage step up or down viaphysical electrical components (e.g., an internal DC/DC converter of thepower transmitter 20). However, while not utilizing hardware internal tothe power transmitter to alter V_(DC), it is certainly contemplated, asdiscussed below, that voltage, current, and/or power levels of theresultant power signal V_(AC) may be altered by control via thecontroller 28.

The external power supply 45 receives an input power V_(IN), which maybe any DC or AC input power, to be conditioned by the external powersupply 45, for output directly to the amplifier 42 as V_(DC). A voltageregulator 46 receives V_(IN) from the input power source 12 and isconfigured to provide electrical power to the amplifier 42. Accordingly,the voltage regulator 46 is configured to convert the receivedelectrical power into a power signal at a proper voltage for operationof the respective downstream components. The voltage regulator 46 may beany voltage regulator known in the art that is capable of converting ininput voltage to an output, direct current voltage, which may includeone or more DC/DC converters, amplifiers, transistors, transformers,inverters, switches, diodes, rectifiers, switching systems, among otherknown voltage regulators. To that end, the voltage regulator 46 may beconfigured to step up V_(IN) to result in V_(DC), step down V_(IN) toresult in V_(DC), and/or maintain a substantially similar voltage V_(IN)to result in V_(DC).

Such stepping up, stepping down, and/or maintenance of the voltage forgenerating V_(DC) may be controlled by a power supply controller 47 ofthe external power supply 45. The power supply controller 47 may includeany internal firm ware and/or may respond to signals from any externalcontrollers (e.g., the transmission controller 28) for determininginstructions for provision to the voltage regulator 46, to controlvoltage levels for the resultant V_(DC). As discussed in more detailbelow, one or more control methods, schemes, and/or components areutilized by the power supply controller 47 to output the desired V_(DC)directly to the amplifier 42.

The power supply controller 47 may be any electronic controller orcomputing system that includes, at least, a processor which performsoperations, executes control algorithms, stores data, retrieves data,gathers data, controls and/or provides communication with othercomponents and/or subsystems associated with external power supply 45,and/or performs any other computing or controlling task desired. Thepower supply controller 47 may be a single controller or may includemore than one controller disposed to control various functions and/orfeatures of the external power supply 45. Functionality of the powersupply controller 47 may be implemented in hardware and/or software andmay rely on one or more data maps relating to the operation of theexternal power supply 45. To that end, the power supply controller 47may be operatively associated with memory. The memory may include one ormore of internal memory, external memory, and/or remote memory (e.g., adatabase and/or server operatively connected to the power supplycontroller 47 via a network, such as, but not limited to, the Internet).The internal memory and/or external memory may include, but are notlimited to including, one or more of a read only memory (ROM), includingprogrammable read-only memory (PROM), erasable programmable read-onlymemory (EPROM or sometimes but rarely labelled EROM), electricallyerasable programmable read-only memory (EEPROM), random access memory(RAM), including dynamic RAM (DRAM), static RAM (SRAM), synchronousdynamic RAM (SDRAM), single data rate synchronous dynamic RAM (SDRSDRAM), double data rate synchronous dynamic RAM (DDR SDRAM, DDR2, DDR3,DDR4), and graphics double data rate synchronous dynamic RAM (GDDRSDRAM, GDDR2, GDDR3, GDDR4, GDDR5, a flash memory, a portable memory,and the like. Such memory media are examples of nontransitory machinereadable and/or computer readable memory media. In some examples, powersupply controller 47 may be an integrated circuit configured to includefunctional elements of one or both of the power supply controller 47 andthe external power supply 45, generally.

As illustrated in FIG. 6, the transmission controller 28 may be utilizedfor communications with one or more of the external power supply 45, thepower supply controller 47, or the amplifier 42, for controlling powerlevels of power signals within the power transmitter 20. Particularly,the transmission controller 28 is configured to provide power controlsignals (P_(con)) to control a power level of the power signal V_(AC),V_(AC) configured for transmission to the power receiver 30. Forcontrolling voltages of one or more of V_(AC), V_(DC), or anyintervening power signals of the power transmitter 20, the transmittercontroller 28 may include, implement, execute firmware to implement,and/or functionally provide a voltage controller 41 and a pulse-widthmodulation signal (PWM) generator 43.

The voltage controller 41 is, generally, configured to provide one orboth of control instructions for stepping up or stepping down the DCpower signal V_(DC) or altering power levels of the AC power signalV_(AC). Further, to determine the power control signals (P_(con)), thevoltage controller may be configured to receive power request signals(P_(req)) from the power receiver 30 and determine P_(con) based, atleast in part, on P_(req). P_(req) may be any information thatdetermines a desired power level for transmission to the power receiver30, such as, but not limited to, a current charge level of a loadassociated with the power receiver 30, a voltage at a rectifier of thepower receiver 30, a load resistance associated with the power receiver30, among other electrical information associated with the powerreceiver 30.

For controlling voltage levels of V_(DC), upon input to the amplifier42, from the external power supply 45, the transmitter controller 28 isconfigured to provide P_(con), at least in part, to the external powersupply 45, such that the power supply may utilize information of P_(con)to configure V_(DC) based, at least in part, on V_(IN) and P_(con), andprovide V_(DC) to the amplifier 42. In some such examples, such as thoseillustrated in FIG. 6A, the power supply controller 47 is configured toreceive P_(con), at least in part, and generate voltage regulationinstructions (V_(reg)), V_(reg) configured for altering the DC voltageof V_(DC), based on P_(con). The power supply controller 47 providesV_(reg) to the voltage regulator 46, for the voltage regulator 46 toregulate and/or control levels of the DC voltage of V_(DC), prior toinput to the amplifier 42.

In some examples, information of P_(con) transmitted to the power supplycontroller 47 may include voltage step up instructions and/or voltagestep down instructions (P_(con_step)). P_(con_step) includes a steplevel, which is a level, step magnitude, and/or change in voltage atwhich the voltage regulator 46 and/or the power supply controller 47 isconfigured to step up or step down the DC voltage of V_(DC), whenconfiguring V_(DC) from V_(IN). In some examples, the step levels may beproprietary, with specific voltage levels configured for operation ofspecific devices and/or operations. In some other examples, the steplevels may be a constant rate of change in voltage, from which the powersupply 45 is configured to any power level that is a multiple of thestep level, up to an upper-bound maximum output power. Utilizing smallstep levels may allow for greater precisionity in power control, by thepower transmitter 20, utilizing external power regulation of theexternal power supply 45. For example, the step level may be in a rangeof about 10 millivolts (mV) to about 500 mV. In some other examples, thestep level may be about 200 mV. Utilizing step levels in control of anexternal power supply 45 may allow for the power transmitter 20 toeffectively utilize off-the-shelf, inexpensive power supplies, in placeof more costly internal voltage regulation hardware.

Turning now to FIG. 6B, the PWM generator 43 may be utilized forproviding a PWM signal to the amplifier, for forming V_(AC) based, atleast in part, on the input V_(DC) of the amplifier 42. The PWMgenerator 43 may generate the PWM signal based, at least, on anoperating frequency provided by the operating frequency generator 48. Insome examples, the operating frequency produced by the operatingfrequency generator 48 may be selected from a range of about 87 kHz toabout 205 kHz.

In some examples, the PWM generator further includes a duty cycle shift49, which may be configured to shift, alter, and/or otherwise configurea duty cycle of the resultant AC power signal V_(AC), which is generatedbased, at least in part, on the PWM signal (PWM). A duty cycle, asdefined herein, refers to the positive voltage cycle of a period of anAC power signal. In an exemplary, ideal, sinusoidal waveform for the ACpower signal V_(AC), the initial duty cycle of V_(AC) is about 50% ofthe period of the sinusoidal waveform. Thus, if the duty cycle of V_(AC)is decreased, the effective amount of power, over a period of time, willbe less than the amount of power output, over a period of time, of anunaltered, about 50% duty cycle for the ideal sinusoidal waveform.

For the purposes of explanation and example, FIG. 6C is provided toillustrate the effect of a duty cycle shift on the power output of theamplifier 42, based on the control systems, schemes, and/or apparatusdisclosed, with respect to FIGS. 6A and 6B. As illustrated in FIGS. 6Aand 6B, the power signal V_(AC) is generated at the amplifier 42 based,at least in part, on both V_(DC) and PWM. As illustrated in FIG. 6C, theoutput of the amplifier, with inputs of V_(DC) and PWM, may result in asubstantially sinusoidal wave form having an initial duty cycle (d_(i))that is equal to about 50% of a period of the sinusoidal waveform (T).As illustrated, this unshifted sinusoidal power signal is an initial ACpower signal (V_(ACi)), which has an initial root mean square voltage(V_(ACi_rms)). A root mean square (rms) voltage refers to the squareroot of the average value of the squared function of instantaneousvalues for the voltage, over a period of time, for an alternatingcurrent signal. In other words, one may consider a rms voltage to referto an equivalent DC value which tells you how many volts of voltageand/or amperes of current that a waveform is comparable to, in terms ofits ability to produce the same power. As illustrated, V_(ACi) has apeak voltage V_(Peak), the initial duty cycle d_(i), and a period T. Ifd_(i) is shifted and V_(Peak) and T remain substantially constant, thenan rms voltage of the wave form will shift proportionately with theshift in duty cycle. To that end, as illustrated in FIG. 6C, if d_(i) isshifted and/or reduced by a shift (s) and substantially maintains aconstant T and V_(Peak), then a rms voltage of the shifted, final outputV_(AC), having a shifted duty cycle d_(shift), will have an altered rmsvoltage (V_(AC_rms)), when compared to V_(ACi_rms).

In some examples, the PWM generator 43 may be configured to receive dutycycle shift information (P_(con) shift), of P_(con), and generate PWM asmodified to generate V_(AC) with a modified duty cycle, as illustratedin FIG. 6C. In such examples, the root mean square voltage V_(AC_rms),after modification, is less than V_(ACi_rms) would be, absent the dutycycle shift. Accordingly, by shifting the duty cycle of V_(AC),utilizing the controller 28 and/or the PWM generator 43, precisioncontrol of the power levels output for V_(AC) can be achieved throughdirect software and/or hardware control of a duty cycle shift forV_(AC).

By utilizing the duty cycle shifting systems, methods, and/or apparatusin conjunction with the external power supply control systems methodsand/or apparatus, precision power level control for an output powersignal can be achieved by the power transmitter 20. Additionally, suchsystems, methods, and/or apparatus may allow for greater precisionity incontrols and/or greater range of controls, without need to includeadditional and/or costly voltage regulation hardware within the powertransmitter 20, itself. As discussed above, said systems, methods, andapparatus are beneficial for utilizing the power transmitter 20 withknown, affordable, off-the-shelf power supply components, for costreduction and/or bill of materials reduction.

Turning now to FIG. 7 and with continued reference to FIGS. 6A-C, ablock diagram for an exemplary method 500 for controlling power inputand/or output of the power transmitter 20 is illustrated. The method 500may begin at block 505, wherein the transmitter controller 28 receivesP_(req) from the power receiver 30. As illustrated in block 510, themethod 500 may include determining P_(con) based on P_(req). Further,the method 500 includes providing P_(con) shift of P_(con) to theexternal power supply 45 and/or any components thereof. The externalpower transmitter 45 determines V_(reg) based, at least, on P_(con)shift (block 520) and determines and provides V_(DC) to the powertransmitter 20 (at the amplifier 42), based on V_(reg) (block 525).

In some examples, such as those best described with reference to FIG.6C, the method 500 may further include determining a duty cycle shiftfor (P_(con) (P_(con_shift)) for further desired voltage configurationof V_(AC), as illustrated in block 530. Further, PWM may then be alteredand/or adjusted, based on P_(con) shift, as illustrated in block 535.

The amplifier 42 is configured to receive the PWM signal from thetransmitter controller 28, as illustrated in block 540. Then, theamplifier 42 generates V_(AC) based, at least in part, on V_(DC) andPWM, as illustrated in block 545.

FIG. 6 is an exemplary schematic diagram 120 for an embodiment of thepower transmitter 20. In the schematic, the amplifier 42 is afull-bridge inverter 142 which drives the transmitter coil 21 and aseries capacitor C_(S). In some examples, wherein the operatingfrequency of the power transmitter 20 is in the range of about 87 kHzand about 205 kHz, the transmitter coil 21 has a self-inductance in arange of about 5 μH to about 7 μH. In some such examples, C_(S) has acapacitance in a range of about 400 nF to about 450 nF.

Based on controls configured by the control and communications system26, an input power source 112, embodying the input power source 12, isaltered to control the amount of power transferred to the power receiver30. The input voltage of the input power source 112 to the full-bridgeinverter 142 may be altered within a range of about 1 volt (V) to about19 V, to control power output. In such examples, the resolution of thevoltage of the input power source 112 may be 10 millivolts (mV) or less.In some examples, when the power transmitter 20, 120 first applies apower signal for transfer to the power receiver 30, the power signal ofthe input power source 112 has an initial input power voltage in a rangeof about 4.5 V to about 5.5 V.

The transmitter coil 21 may be of a wire-wound type, wound of, forexample, Litz wire. As defined herein, Litz wire refers to a type ofmultistrand wire or cable utilized in electronics to carry analternating current at a frequency. Litz wire is designed to reduce skineffect and proximity effect losses in conductors at frequencies up toabout 1 MHz and consists of many thin wire strands, individuallyinsulated and twisted or woven together, following a pattern. In someexamples, the Litz wire may be no. 17 American Wire Gauge (AWG) (1.15mm) type 2 Litz wire, having 105 strands of no. 40 AWG (0.08 mmdiameter), or equivalent wire. In some examples, the Litz wire used forthe transmitter coil 21 may be a bifilar Litz wire. To that end,utilizing thicker Litz wire, such as the no. 17 AWG type 2 Litz wire,utilizing bifilar Litz wire, and combinations thereof, may result in anincreased Quality Factor (Q) for the transmitter coil 21 and higher Qmay be directly related to increases in gap 17 height and/or Z-Distance.As Q is directly related to the magnitude of the magnetic field producedby the transmitter antenna 21 and, thus, with a greater magnitudemagnetic field produced, the field emanating from the transmissionantenna 21 can reach greater Z-distances and/or charge volumes, incomparison to legacy transmission coils, having lower Q designs. WhileLitz wire is described and illustrated, other equivalents and/orfunctionally similar wires may be used. Furthermore, other sizes andthicknesses of Litz wire may be used.

Turning to FIG. 7, an exemplary diagram 121, for portraying dimensionsof the transmitter antenna 21, is illustrated. The diagram 121 is a topperspective view of the transmitter antenna 21 and shows a top face 60of the transmitter antenna 21. Note that the diagram 121 is notnecessarily to scale and is for illustrative purposes. The top face 60and the transmitter antenna 21, generally, are relatively circular inshape. As illustrated, an outer diameter d_(o) is defined as an exteriordiameter of the transmitter antenna 21. In some examples, the outerdiameter d_(o) has an outer diameter length in a range of about 40 mm toabout 50 mm. An inner diameter d_(i) is defined as the diameter of thevoid space in the interior of the transmitter antenna 21. The innerdiameter d_(i) may have an inner diameter length in a range of about 15mm to about 25 mm. The outer diameter d_(o) and the inner diameter d_(i)may be relatively concentric, with respect to one another. Thetransmitter coil 21 has a thickness t_(w), which is defined as thethickness of the wire of the coil. The thickness t_(w) may be in a rangeof about 2 mm to about 3 mm. In such examples, the transmitter coil 21may be made of Litz wire and include at least two layers, the at leasttwo layers stacked upon each other. Utilization of one or more of anincreased inner diameter d_(i), an increased outer diameter d_(o),multiple Litz wire layers for the antenna 21, specific dimensionsdisclosed herein, and/or combinations thereof, may be beneficial inachieving greater gap 17 heights and/or Z-distances. Other shapes andsizes of the transmitter antenna 21 may be selected based on theconfiguration with the selection of the shape and size of the shieldingof the transmitter coil. In the event that a desired shielding inrequired, the transmitter antenna 21 may be shaped and sized such thatthe shielding surrounds the transmitter antenna 21 in accordance with anembodiment.

Turning now to FIG. 8, a cross-sectional view of the transmitter coil21, within the base station 11 and partially surrounded by a shielding80 of the transmitter coil 21, is illustrated. The shielding 80comprises a ferrite core and defines a cavity 82, the cavity configuredsuch that the ferrite core substantially surrounds all but the top face60 of the transmitter antenna 21 when the transmitter antenna 21 isplaced in the cavity. As used herein, “surrounds” is intended to includecovers, encircles, enclose, extend around, or otherwise provide ashielding for. “Substantially surrounds,” in this context, may take intoaccount small sections of the coil that are not covered. For example,power lines may connect the transmitter coil 21 to a power source. Thepower lines may come in via an opening in the side wall of the shielding80. The transmitter coil 21 at or near this connection may not becovered. In another example, the transmitter coil 21 may rise slightlyout of the cavity and thus the top section of the side walls may not becovered. By way of example, substantially surrounds would includecoverage of at least 50+% of that section of the transmitter antenna.However, in other examples, the shielding may provide a greater orlesser extent of coverage for one or more sides of the transmitterantenna 21.

In an embodiment, as shown in FIG. 8, the shielding 80 surrounds atleast the entire bottom section of the transmitter antenna 21 and almostall of the side sections of the transmitter antenna 21. As used herein,the entire bottom section of the transmitter antenna 21 may include, forexample, the entire surface area of the transmitter antenna 21 or all ofthe turns of the Litz wire of the transmitter antenna 21. With respectto the side walls, as shown in FIG. 8, the magnetic ring 84 does notextend all the way up the side wall of the transmitter antenna 21.However, as shown in other illustrations, the side wall may extend allthe way up the side wall.

In another embodiment, the shielding 80 may surround less than theentire bottom section of the transmitter antenna 21. For example,connecting wires (e.g., connecting wires 292, as best illustrated inFIGS. 10A, 10B and discussed below) may be run through an opening in thebottom of the shielding 80.

In an embodiment, as shown in FIG. 8, the shielding 80 is an “E-Core”type shielding, wherein the cavity 82 and structural elements of theshielding 80 are configured in an E-shape configuration, when theshielding is viewed, cross-sectionally, in a side view. The E-Coreconfiguration is further illustrated in FIG. 9, which is a perspectiveview of the shielding 80. The shielding 80 may include a magnetic core86, a magnetic backing 85, and a magnetic ring 84. The magnetic core 86is spaced inwardly from the outer edge of the magnetic backing 85 andprojects in an upward direction from the top surface of the magneticbacking 85. The magnetic core 86 and the magnetic ring 84 function tosurround the transmitter coil 21 and to direct and focus magneticfields, hence improving coupling with the receiver coil 31 of the powerreceiver 30.

In addition to covering the entire outer diameter of the transmittercoil 21, the shielding 80 may also cover the inner diameter d_(i) of thetransmitter coil 21. That is, as shown, the inner section of the E-Coreconfiguration may protrude upward through the middle of the transmittercoil 21.

In an embodiment, the cavity 82 is configured such that the shielding 80covers the entire bottom section of the transmitter coil 21 and theentire side sections of the transmitter coil 21. The top section of thetransmitter coil 21 is not covered. The bottom section of thetransmitter coil 21 is the side of the transmitter coil 21 that isopposite of the direction of the primary power transfer to the receivercoil. With a wire wound transmitter coil 21, the side section of thetransmitter coil 21 includes the side section of the outer most windingof the coil 21.

FIG. 10A is a perspective view of the transmitter coil 21 and theembodiment of the E-core shielding of FIG. 9 and FIG. 10B is an explodedperspective view of the transmitter coil 21 and the embodiment of theE-core shielding of FIG. 9. The transmitter coil 21 is positioned abovethe shielding 80, whose combination of structural bodies, as discussedabove, may include the combination of the magnetic core 86, the magneticbacking 85, and magnetic ring 84. This magnetic shielding combinationfunctions to help direct and concentrate magnetic fields created bytransmitter coil 21 and can also limit side effects that would otherwisebe caused by magnetic flux passing through nearby metal objects. In someexamples, the magnetic ring defines an opening 88, in which a connectingwire 292 of the transmitter coil 21 can exit the shielding 80.

As defined herein, a “shielding material,” from which the shielding 80is formed, is a material that captures a magnetic field. An example ofwhich is a ferrite material. The ferrite shield material selected forthe shielding 80 also depends on the operating frequency, as the complexmagnetic permeability (μ=μ′−j*μ″) is frequency dependent. The materialmay be a sintered flexible ferrite sheet or a rigid shield and becomposed of varying material compositions. In some examples, the ferritematerial for the shielding 80 may include a Ni—Zn ferrite, a Mn—Znferrite, and any combinations thereof.

Returning now to FIG. 8 and with continued reference to FIGS. 9 and 10,the shielding 80 is aligned with the transmitter antenna 21 such thatthe shielding 80 substantially surrounds the transmitter antenna 21 onall sides, aside from the top face 60. In other words, the transmitterantenna 21 may be wound around the magnetic core 86 and be surrounded,on the bottom and sides, respectively, by the magnetic backing 85 andthe magnetic ring 84. As illustrated, the shielding 80, in the form ofone or both of the magnetic backing and the magnetic core, may extendbeyond the outer diameter d_(o) of the transmitter antenna 21 by ashielding extending distance d_(e). In some examples, the shieldingextending distance d_(e) may be in a range of about 5 mm to about 6 mm.The shielding 80, at the magnetic backing 85, and the transmitter coil21 are separated from one another by a separation distance d_(s), asillustrated. In some examples, the separation distance d_(s) may be in arange of about 0.1 mm and 0.5 mm.

An interface surface 70 of the base station 11 is located at aninterface gap distance d_(int) from the transmitter coil 21 and theshielding 80. The interface surface 70 is a surface on the base station11 that is configured such that when a power receiver 30 is proximate tothe interface surface 70, the power receiver 30 is capable of couplingwith the power transmitter 20, via near-field magnetic induction betweenthe transmitter antenna 21 and the receiver antenna 31, for the purposesof wireless power transfer. In some examples, the interface gap distanced_(int) maybe in a range of about 8 mm to about 10 mm. In such examples,the d_(int) is greater than the standard required Z-distance for Qi™certified wireless power transmission (3-5 mm). Accordingly, by having agreater d_(int), empty space and/or an insulator can be positionedbetween the transmission coil 21 and the interface surface 70 tomitigate heat transfer to the interface surface 70, the power receiver30, and/or the electronic device 14 during operation. Further, such agreater d_(int) allows for interface design structures in which objectson or attached to the electronic device 14 may remain attached to theelectronic device during operation. As described in greater detailbelow, design features of the interface surface 70 may be included forinteraction with such objects for aligning the power transmitter 20 andthe power receiver 30 for operation.

Returning now to FIG. 10B, an exemplary coil 221 for use as thetransmitter antenna 21 is illustrated in the exploded view of thetransmitter antenna 21 and shielding 80. The coil 221 includes one ormore bifilar Litz wires 290 for the first bifilar coil layer 261 and thesecond bifilar coil layer 262. “Bifilar,” as defined herein, refers to awire having two closely spaced, parallel threads and/or wires. Each ofthe first and second bifilar coil layers 261, 262 include N number ofturns. In some examples, each of the first and second bifilar coillayers 261, 262 include about 4.5 turns and/or the bifilar coil layers261, 262 may include a number of turns in a range of about 4 to about 5.In some examples, the one or more bifilar Litz wire 290 may be no. 17AWG (1.15 mm) type 2 Litz wire, having 105 strands of no. 40 AWG (0.08mm diameter), or equivalent wire. Utilization of multiple layers, thickLitz wire, bifilar Litz wire, and any combinations thereof, may resultin the coil 21 achieving greater Q and/or may result in increases in gap17 height and/or Z-distance between the coil 21 and a receiver coil.

FIG. 11A is a first block diagram 311A for an implementation of the basestation 11. As illustrated, the power transmitter 20 is contained withinthe base station 11. In some examples, the base station 11 includes oneor more user feedback mechanisms 300, wherein each of the one or moreuser feedback mechanisms 300 are configured for aiding a user inaligning a power receiver 30 and/or its associated electronic device 14with an active area 310 for wireless power transmission via thetransmitter coil 21, wherein the power receiver 30 is configured toacquire near field inductive power from the transmitter coil 21. The“active area” 310, as defined herein, refers to any area, volume, and/orspace proximate to the interface surface 70 wherein the powertransmitter 20 is capable of transmitting near field inductive power toa power receiver 30.

The one or more user feedback mechanisms 300 may include one or more ofa visual feedback display 302, a tactile feedback mechanism 304, anaudible feedback mechanism 306, a marking 308 on the interface surface70, any other feedback mechanisms 300, and any combinations thereof. Thevisual feedback display 302 is configured for visually indicating properalignment of the power receiver 30 with the active area 310. The visualfeedback display 302 may include, but is not limited to including, avisual screen, a light, a light emitting diode (LED), a liquid crystaldisplay (LCD) display, other visual displays, and/or any combinationsthereof. The tactile feedback mechanism 304 is configured for tactilelyindicating if the power receiver 30 is in proper alignment with theactive area 310. The tactile feedback mechanism 304 may include, but isnot limited to including, a haptic feedback device, a vibrating device,other tactile feedback mechanisms, and any combinations thereof. Theaudible feedback device 306 is configured for audibly indicating if thepower receiver 30 is in proper alignment with the active area 310. Theaudio feedback mechanism 306 may include, but is not limited toincluding, a speaker, a sound generator, a voice generator, an audiocircuit, an amplifier, other audible feedback devices, and anycombinations thereof.

The marking 308 may be any visual and/or mechanical signifier,indicating where a user of the electronic device 14 should placehis/her/their electronic device 14 on the interface surface 70, suchthat the power transmitter 20 will be in proper alignment with the powerreceiver 30 of the electronic device 14. Additionally or alternatively,the marking 308 may indicate a location of the active area 310 and/or aproper location within the active area 70. In the exemplary embodimentof the diagram 311A, the marking 308A may be a substantiallytwo-dimensional visual indicator marked on the interface surface 70. Thesubstantially two-dimensional marking 308A may include, but is notlimited to including, a printed indicator, a logo, a message indicatinga user should place the electronic device 14 upon the marking 308A, anyother substantially two-dimensional markings, and any combinationsthereof.

In an alternative embodiment in a second schematic block diagram 311Billustrated in FIG. 11B, the marking 308B is a substantiallythree-dimensional and/or mechanical marking 308B, such as, but notlimited to, an indentation and/or notch in the interface surface 70. Thethree-dimensional marking 308B may be configured to interact withmechanical feature 72 of the electronic device 14. The mechanicalfeature 72 may be any mechanical feature of the electronic device 14and/or another connected mechanical feature and/or device associatedwith the electronic device 14. Accordingly, interaction between themechanical feature 72 and the three-dimensional marking 308B may beconfigured to align the power transmitter 20 with the power receiver 30of the electronic device 14. For example, the mechanical feature 72 maybe an external protrusion located relatively proximate to the powerreceiver 30 of electronic device 14 and the marking 308B is configuredto receive the mechanical feature and, by the nature of such receipt,the power transmitter 20 and the power receiver 30 are properly alignedfor near-field inductive wireless power transfer. In some such examples,the electronic device 14 is a mobile device, such as a smart phoneand/or tablet computing device, and the mechanical feature 72 may be anexternally attached grip device configured for gripping the electronicdevice 14 when in use. In such examples, the marking 308B is configuredto receive the grip device mechanical feature 72 and enable properalignment of the power transmitter 20 and the power receiver 30 fornear-field inductive wireless power transfer while the removablemechanical feature 72 remains attached to the electronic device 14.

FIG. 12 is an exemplary, actual, simulation 400 of a magnetic fieldgenerated by a transmitter coil 21 and/or its associated powertransmitter 20 and captured by an exemplary receiver coil 31 and/or itsassociated power receiver 30, when the transmitter coil 21 and/or powertransmitter 20 are designed, manufactured, and/or implemented accordingto the teachings of this disclosure. The receiver coil 30 was as astandard Qi™ receiver coil utilized by commercial electronic devices,such as mobile phones, and the receiver coil 30 was modelled with ametal piece behind the coil, wherein the metal piece was used tosimulate a battery. The simulation shows that the magnetic fieldgenerated by the transmitter coil 20 was captured by the receiver coil30 at an extended Z-distance of 9 mm. As discussed previously, Qi™wireless transmitter coils typically operate between coil-to-coildistances of about 3 mm to about 5 mm. The shaped-magnetics of thetransmitter coil 21 have shown to favorably reshape a magnetic field sothat coil-to-coil coupling can occur at extended Z-distances, whereinthe Z-distances are extended about 2 times to about 5 times the distanceof standard Qi™ wireless power transmitters. Furthermore, theshaped-magnetics of the present application can extend coupling ofpresent day a Qi™ wireless power transmitter at a Z-distance rangingabout 5 mm to about 25 mm. Any of the E-core and/or additional oralternative custom shapes for the shielding 80, may successfully be usedto reshape the magnetic field for extended Z-distance coupling by aminimum of a 5% compared to standard present-day power transmitters. Inaddition, any of the E-core and custom shapes previously discussed, eachin conjunction with its relation to a coil to the magnetic has also mayfurther increase z-direction coupling by at least another 5%. Anembodiment comprising a structure, the structure comprising a coil and amagnetic material, wherein a gap between the coil and the magneticmaterial residing at the inner diameter of the coil comprises 2 mm,reshapes the magnetic field so that coupling increases by 5%.

As is discussed above, the transmitter coils 21, power transmitters 20,and/or base stations 11, disclosed herein, may achieve greatadvancements in Z-distance and/or gap 17 height, when compared tolegacy, low-frequency (e.g., in a range of about 87 kHz to about 205kHz) transmission coils, power transmitters, and/or base stations. Tothat end, an extended Z-distance not only expands a linear distance,within which a receiver may be placed and properly coupled with atransmitter, but an extended Z-distance expands a three-dimensionalcharging and/or operational volume (“charge volume”), within which areceiver may receive wireless power signals from a transmitter. For thefollowing example, the discussion fixes lateral spatial freedom (X and Ydistances) for the receiver coil, positioned relative to the transmittercoil, as a control variable. Accordingly, for discussion purposes only,one assumes that the X and Y distances for the base stations 11, powertransmitters 20, and/or transmitter coils 21 are substantially similarto the X and Y distances for the legacy system(s). However, it iscertainly contemplated that the inventions disclosed herein may increaseone or both of the X-distance and Y-distance. Furthermore, while theinstant example uses the exemplary range of 8-10 mm for the Z-distanceof the base stations 11, power transmitters 20, and/or transmitter coils21, it is certainly contemplated and experimental results have shownthat the base stations 11, power transmitters 20, and/or transmittercoils 21 are certainly capable of achieving Z-distances having a greaterlength than about 10 mm, such as, but not limited to, up to 15 mm and/orup to 30 mm. Accordingly, the following table is merely exemplary andfor illustration that the expanded Z-distances, achieved by the basestations 11, power transmitters 20, and/or transmitter coils 21, havenoticeable, useful, and beneficial impact on a charge volume associatedwith one or more of the base stations 11, power transmitters 20, and/ortransmitter coils 21.

Spatial Freedom Comparison Charge Charge X- Y- Z-dist Z-dist Vol. Vol.dist dist (min) (max) (min) (max) Legacy 5 mm 5 mm  3 mm  5 mm  75 mm³125 mm³ 11, 20, 21 5 mm 5 mm  8 mm 10 mm 200 mm³ 250 mm³ (8-10 mm. ver.)11, 20, 21 5 mm 5 mm 10 mm 15 mm 250 mm³ 375 mm³ (15 mm. ver.) 11, 20,21 5 mm 5 mm 15 mm 30 mm 375 mm³ 750 mm³ (30 mm. ver.)

Thus, by utilizing the base stations 11, power transmitters 20, and/ortransmitter coils 21, the effective charge volume may increase by morethan 100 percent, when compared to legacy, low-frequency wireless powertransmitters. Accordingly, the base stations 11, power transmitters 20,and/or transmitter coils 21 may achieve large Z-distances, gap heights,and/or charge volumes that were not possible with legacy low frequency,but thought only possible in lower power, high frequency (e.g., aboveabout 2 Mhz) wireless power transfer systems.

FIG. 13 is an example block diagram for a method 1200 for designing thepower transmitter 20. The method 1200 includes designing and/orselecting the transmitter coil 21 for the power transmitter 20, asillustrated in block 1210. The method 1200 includes tuning the powertransmitter 20, as illustrated in block 1220. Such tuning may beutilized for, but not limited to being utilized for, impedance matching.

The method 1200 further includes designing the power conditioning system40 for the power transmitter 20, as illustrated in block 1230. The powerconditioning system 40 may be designed with any of a plurality of poweroutput characteristic considerations, such as, but not limited to, powertransfer efficiency, maximizing a transmission gap (e.g., the gap 17),increasing output voltage to a receiver, mitigating power losses duringwireless power transfer, increasing power output without degradingfidelity for data communications, optimizing power output for multiplecoils receiving power from a common circuit and/or amplifier, amongother contemplated power output characteristic considerations. Further,at block 1240, the method 1200 may determine and optimize a connection,and any associated connection components, to configure and/or optimize aconnection between the input power source 12 and the power conditioningsystem 40 of block 1230. Such determining, configuring, and/oroptimizing may include selecting and implementing protection mechanismsand/or apparatus, selecting and/or implementing voltage protectionmechanisms, among other things.

The method 1200 further includes designing and/or programing the controland communications system 26 of the power transmitter 20, as illustratedin block 1250. Components of such designs include, but are not limitedto including, the sensing system 50, the driver 41, the transmissioncontroller 28, the memory 27, the communications system 29, the thermalsensing system 52, the object sensing system 54, the receiver sensingsystem 56, the electrical sensor(s) 57, the other sensor(s) 58, in wholeor in part and, optionally, including any components thereof.

FIG. 14 is an example block diagram for a method 2200 for manufacturingthe power transmitter 20. The method 2200 includes manufacturing and/orselecting the transmitter coil 21 for the power transmitter 20, asillustrated in block 2210. The method 2200 includes tuning the powertransmitter 20, as illustrated in block 2220. Such tuning may beutilized for, but not limited to being utilized for, impedance matching.

The method 2200 further includes manufacturing the power conditioningsystem 40 for the power transmitter 20, as illustrated in block 2230.The power conditioning system 40 may be designed and/or manufacturedwith any of a plurality of power output characteristic considerations,such as, but not limited to, power transfer efficiency, maximizing atransmission gap (e.g., the gap 17), increasing output voltage to areceiver, mitigating power losses during wireless power transfer,increasing power output without degrading fidelity for datacommunications, optimizing power output for multiple coils receivingpower from a common circuit and/or amplifier, among other contemplatedpower output characteristic considerations. Further, at block 2240, themethod 2200 may include connecting and/or optimizing a connection, andany associated connection components, to configure and/or optimize aconnection between the input power source 12 and the power conditioningsystem 40 of block 2230. Such determining, manufacturing, configuring,and/or optimizing may include selecting and implementing protectionmechanisms and/or apparatus, selecting and/or implementing voltageprotection mechanisms, among other things.

The method 2200 further includes designing and/or programing the controland communications system 26 of the power transmitter 20, as illustratedin block 2250. Components of such designs include, but are not limitedto including, the sensing system 50, the driver 41, the transmissioncontroller 28, the memory 27, the communications system 29, the thermalsensing system 52, the object sensing system 54, the receiver sensingsystem 56, the electrical sensor(s) 57, the other sensor(s) 58, in wholeor in part and, optionally, including any components thereof.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

The predicate words “configured to”, “operable to”, and “programmed to”do not imply any particular tangible or intangible modification of asubject, but, rather, are intended to be used interchangeably. In one ormore embodiments, a processor configured to monitor and control anoperation or a component may also mean the processor being programmed tomonitor and control the operation or the processor being operable tomonitor and control the operation. Likewise, a processor configured toexecute code can be construed as a processor programmed to execute codeor operable to execute code.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as an “aspect” may refer to one or more aspects and vice versa. Aphrase such as an “embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such an “embodiment” may refer to one or more embodiments andvice versa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as a “configuration” may referto one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” or as an “example” is not necessarily to be construed aspreferred or advantageous over other embodiments. Furthermore, to theextent that the term “include,” “have,” or the like is used in thedescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprise” as “comprise” is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “include,” “have,” or the like is used in the descriptionor the claims, such term is intended to be inclusive in a manner similarto the term “comprise” as “comprise” is interpreted when employed as atransitional word in a claim.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112, sixth paragraph, unless theelement is expressly recited using the phrase “mean for” or, in the caseof a method claim, the element is recited using the phrase “step for.”

Reference to an element in the singular is not intended to mean “one andonly one” unless specifically so stated, but rather “one or more.”Unless specifically stated otherwise, the term “some” refers to one ormore. Pronouns in the masculine (e.g., his) include the feminine andneuter gender (e.g., her and its) and vice versa. Headings andsubheadings, if any, are used for convenience only and do not limit thesubject disclosure.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of what may be claimed, but ratheras descriptions of particular implementations of the subject matter.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub-combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to a subcombination or variation of a sub combination.

What is claimed is:
 1. A power transmitter for wireless power transferat an operating frequency selected from a range of about 87 kilohertz(kHz) to about 205 kHz, the power transmitter comprising: a control andcommunications unit configured to: provide power control signals to apower supply external to the power transmitter, for controlling a powerlevel of an alternating current (AC) power signal configured fortransmission to a power receiver, the AC power signal having an initialroot mean square voltage, the power supply configured to configure adirect current (DC) power based on the power control signals andincluding a voltage regulator and a power supply controller configuredto receive the power control signals, generate voltage regulationinstructions for altering a DC voltage of the DC power, based on thepower control signals, and provide the voltage regulation instructionsto the voltage regulator to control the DC voltage of the DC power,wherein the voltage regulation instructions include voltage step upinstructions or voltage step down instructions for the voltageregulator, the voltage step up instructions and voltage step downinstructions having a step level, the step level being a change involtage at which the voltage regulator is configured to step up or stepdown the DC voltage of the DC power for the purposes of configuring theinitial root mean square voltage of the AC power signal, and generate apulse width modulation signal for configuring an AC frequency for the ACpower signal, at the operating frequency, the pulse width modulationsignal modified by a duty cycle alteration, the duty cycle alterationconfigured to decrease the initial root mean square voltage of the ACpower signal to a shifted root mean square voltage, the shifted rootmean square voltage being less than the initial root mean squarevoltage; an inverter circuit configured to receive DC power from thepower supply external to the power transmitter and convert the DC powerto the AC power signal based on the pulse width modulation signal; and acoil configured to transmit the AC power signal to the power receiver,the coil formed of wound Litz wire and including at least one layer. 2.The power transmitter of claim 1, wherein the control and communicationsunit is further configured to receive power request signals from thepower receiver, and determine the power control signals based on thepower request signals.
 3. The power transmitter of claim 1, wherein thepower supply is configured to: configure an input DC power to generatethe DC power supplied based on the power control signals, and providethe DC power to the inverter circuit.
 4. The power transmitter of claim1, wherein the step level is in a range of about 10 millivolts (mV) toabout 500 mV.
 5. The power transmitter of claim 1, wherein the steplevel is about 200 mV.
 6. The power transmitter of claim 1, wherein theduty cycle alteration is further configured to alter an amount of powertransmitted to the power receiver over a period of time.
 7. A powertransmitter for wireless power transfer at an operating frequencyselected from a range of about 87 kilohertz (kHz) to about 205 kHz, thepower transmitter comprising: a control and communications unitconfigured to: provide power control signals to a power supply externalto the power transmitter for controlling a power level of an alternatingcurrent (AC) power signal configured for transmission to a powerreceiver, the AC power signal having an initial root mean squarevoltage, the power supply configured to configure a direct current (DC)power based on the power control signals and including a voltageregulator and a power supply controller configured to receive the powercontrol signals, and generate voltage regulation instructions foraltering a DC voltage of the DC power, based on the power controlsignals, and provide the voltage regulation instructions to the voltageregulator to control the DC voltage of the DC power, wherein the voltageregulation instructions include voltage step up instructions or voltagestep down instructions for the voltage regulator, the voltage step upinstructions and voltage step down instructions having a step level, thestep level being a change in voltage at which the voltage regulator isconfigured to step up or step down the DC voltage of the DC power forthe purposes of configuring the initial root mean square voltage of theAC power signal, and generate a pulse width modulation signal forconfiguring an AC frequency for the AC power signal, at the operatingfrequency, the pulse width modulation signal modified by a duty cyclealteration, the duty cycle alteration configured to decrease the initialroot mean square voltage of the AC power signal to a shifted root meansquare voltage, the shifted root mean square voltage being less than theinitial root mean square voltage; an inverter circuit configured toreceive DC power from the power supply external to the power transmitterand convert the DC power to the AC power signal based on the pulse widthmodulation signal; a coil configured to transmit the AC power signal tothe power receiver, the coil formed of wound Litz wire and including atleast one layer, the coil defining, at least, a top face; and ashielding comprising a ferrite core and defining a cavity, the cavityconfigured such that the ferrite core substantially surrounds all butthe top face of the coil.
 8. The power transmitter of claim 7, whereinthe shielding is an E-Core type shielding and the cavity is configuredin an E-shape configuration.
 9. The power transmitter of claim 7,wherein a shielding outer edge of the shielding extends about 4.5millimeters (mm) to about 6.5 mm outward from a coil outer edge of thecoil.
 10. The power transmitter of claim 7, wherein the coil has anouter diameter length in a range of about 40 mm to about 50 mm.
 11. Thepower transmitter of claim 7, wherein the coil has an inner diameterlength in a range of about 15 mm to about 25 mm.
 12. The powertransmitter of claim 7, wherein the at least one layer comprises a firstlayer and a second layer.
 13. The power transmitter of claim 12, whereinthe first layer includes a first number of turns in a range of about 4turns to about 5 turns, and wherein the second layer includes a secondnumber of turns in a range of about 4 turns to about 5 turns.
 14. Asystem for wireless power transfer at an operating frequency selectedfrom a range of about 87 kilohertz (kHz) to about 205 kHz, the systemcomprising: a power supply that is external to a power transmitter; andthe power transmitter including: a control and communications unitconfigured to: provide power control signals for controlling a powerlevel of an alternating current (AC) power signal configured fortransmission to a power receiver, the AC power signal having an initialroot mean square voltage, and generate a pulse width modulation signalfor configuring an AC frequency for the AC power signal, at theoperating frequency, the pulse width modulation signal modified by aduty cycle alteration, the duty cycle alteration configured to decreasethe initial root mean square voltage of the AC power signal to a shiftedroot mean square voltage, the shifted root mean square voltage beingless than the initial root mean square voltage, an inverter circuitconfigured to receive a direct current (DC) power from the power supplyexternal to the power transmitter and convert the DC power to the ACpower signal based on the pulse width modulation signal, a coilconfigured to transmit the AC power signal to the power receiver, thecoil formed of wound Litz wire and including at least one layer, thecoil defining, at least, a top face, and a shielding comprising aferrite core and defining a cavity, the cavity configured such that theferrite core substantially surrounds all but the top face of the coil,and wherein the power supply external to the power transmitter isconfigured to configure the DC power based on the power control signals,the power supply including: a voltage regulator, and a power supplycontroller configured to: receive the power control signals, generatevoltage regulation instructions for altering the DC power, based on thepower control signals, the voltage regulation instructions includingvoltage step up instructions or voltage step down instructions for thevoltage regulator, the voltage step up instructions and voltage stepdown instructions having a step level, the step level being a change involtage at which the voltage regulator is configured to step up or stepdown a DC voltage of the DC power, and provide the voltage regulationinstructions to the voltage regulator to control a DC voltage of the DCpower.
 15. The system of claim 14, wherein the step level is in a rangeof about 10 millivolts (mV) to about 500 mV.
 16. The system of claim 14,wherein the step level is about 200 mV.